Trigger cable lowers temperatures & power consumption

[Axel]

So do I. 
I remember, some time ago when trying to download configuration files, that once the master config had downloaded, the companion config would fail to download properly. Please try this: Remake your new configuration from scratch. When you have done so, ignore the master configuration (which in your case seems to be OK) and download only the one for the companion, which I think is the one that is not downloading properly and is causing the malfunction.
Good luck with this, it must be driving you up the wall.

I haven’t tried that method, I will give it a go and will come back with the results. Thanks.

I tried the method Axel suggested and it works! Thanks a lot. So the configuration page is to blame for both units not linking despite all connections being correct. The other issue I had is still a mystery, I hope that after resetting and adjusting the Ethernet connection it won’t come back.

Glad you got it sorted!